BFG 866 Running Fast

[Robbie010]

I’ve put my BFG 866 movement back together today, give it a wind and set it going. Using the stop watch on my phone, the watch is running around 10 seconds fast over 60 seconds. 

I’ve tried regulating the watch but it does not seem to make much difference and if I turn the regulator too close to the H/S pin the balance just stops. 

I’m a little stumped here.... any thoughts?

[noirrac1j]

13 minutes ago, Robbie010 said:

I’ve put my BFG 866 movement back together today, give it a wind and set it going. Using the stop watch on my phone, the watch is running around 10 seconds fast over 60 seconds. 

I’ve tried regulating the watch but it does not seem to make much difference and if I turn the regulator too close to the H/S pin the balance just stops. 

I’m a little stumped here.... any thoughts?

Hello,

Check for fouling of the coils: they may be rubbing somewhere, reducing the effective length, or there is oil making them stick.

 

J

[watchweasol]

Hi In addition to the above mentioned points also check that the spring is not bearing on the regulator pins , I should beat evenly between the pins.

[Nucejoe]

 Have you demaged?

Its a hairspring issue, sticking, rubbing, short length or wrong spring.

So a bit of history might helps. 

[Robbie010]

I’m obviously going wrong here somewhere. 

I removed the balance and cleaned it in some essence and adjusted the spring collet slightly which allowed me to regulate it down to around 5 seconds over 5 minutes. However, if you look at the image below, it still looks as though the spring is too tight.... When I install the balance the impulse stone naturally rests between the pallet posts but the spring does not sit right. 

As you can see by the way the spring is stretched out, it looks as though the spring needs unwinding??

When I received the new balance I had to rotate the spring so that the impulse stone sat between the pallet posts and I’m now thinking this is the cause of the issue???

[Robbie010]

Thanks all!

It took some fettling but I now have it running close to an acceptable rate and I should hopefully be able to regulate it.